In one aspect, this invention relates to biomaterials formed ex vivo for implantation and use within the body. In another aspect, the invention relates to in situ curable biomaterials. In yet another aspect, this invention further relates to the field of orthopedic implants and prostheses, and more particularly, for implantable materials for use in orthopedic joints.
Applicant has previously described, inter alia, prosthetic implants formed of biomaterials that can be delivered and finally cured in situ, e.g., using minimally invasive techniques. See for instance, U.S. Pat. Nos. 5,556,429, 5,795,353, 5,888,220, 6,079,868, 6,140,452, 6,224,630 and 6,248,131 as well as published International Application Nos. WO 95/30388 and WO 97/26847 and International Application PCT/US97/20874 filed Nov. 14, 1997 (the disclosures of each of which are incorporated herein by reference). Certain of these applications describe, inter alia, the formation of a prosthetic nucleus within an intervertebral disc by a method that includes, for instance, the steps of inserting a collapsed mold apparatus (which in a preferred embodiment is described as a xe2x80x9cballoonxe2x80x9d) through a cannula that is itself positioned through an opening within the annulus, and filling the balloon with a flowable biomaterial that is adapted to finally cure in situ and provide a permanent disc replacement. See also, Applicant""s xe2x80x9cPorous Biomaterial and Biopolymer Resurfacing Systemxe2x80x9d (PCT/US99/10004), as well as xe2x80x9cImplantable Tissue Repair Device (PCT/US99/11740), and xe2x80x9cStatic Mixerxe2x80x9d (PCT/US99/04407) applications.
See also, U.S. Pat. No. 3,030,951 (Mandarino), U.S. Pat. No. 4,203,444 (Bonnell et al.), U.S. Pat. No. 4,456,745 (Rajan), U.S. Pat. No. 4,463,141 (Robinson), U.S. Pat. No. 4,476,293 (Robinson), U.S. Pat. No. 4,477,604 (Oechsle, III), U.S. Pat. No. 4,647,643 (Zdrahala), U.S. Pat. No. 4,651,736 (Sanders), U.S. Pat. No. 4,722,948 (Sanderson), U.S. Pat. No. 4,743,632 (Marinovic et al.), U.S. Pat. No. 4,772,287 (Ray et al.), U.S. Pat. No. 4,808,691 (Kxc3x6nig et al.), U.S. Pat. No. 4,880,610 (Constanz), U.S. Pat. No. 4,873,308 (Coury et al.), U.S. Pat. No. 4,969,888 (Scholten et al.), U.S. Pat. No. 5,007,940 (Berg), U.S. Pat. No. 5,067,964 (Richmond et al.), U.S. Pat. No. 5,082,803 (Sumita), U.S. Pat. No. 5,108,404 (Scholten et al.), U.S. Pat. No. 5,109,077 (Wick), U.S. Pat. No. 5,143,942 (Brown), U.S. Pat. No. 5,166,115 (Brown), U.S. Pat. No. 5,254,662 (Szycher et al.), U.S. Pat. No. 5,278,201 (Dunn et al.), U.S. Pat. No. 5,525,418 (Hashimoto et al.), U.S. Pat. No. 5,624,463 (Stone et al.), U.S. Pat. No. 6,206,927 (Fell), and EP 0 353 936 (Cedar Surgical), EP 0 505 634 A1 (Kyocera Corporation), EP 0 521 573 (Industrial Res.), and FR 2 639 823 (Garcia), WO 93/11723 (Regen Corporation), WO 9531946 (Milner), WO 9531948 (Kuslich).
Applicant""s PCT Application No. PCT/US97/00457 (WO 9726847A1) includes the optional use of a mold, such as a balloon, and describes the manner in which xe2x80x9c[t]he mold created within the joint is preferably of sufficient shape and dimensions to allow the resulting cured biomaterial to replace or mimic the structure and function of the removed fibrocartilage. The mold can be formed of synthetic and/or natural materials, including those that are provided exogenously and those provided by the remaining natural tissues. The mold can either be removed from the site, upon curing of the biomaterial, or is sufficiently biocompatible to allow it to remain in position.xe2x80x9d
Applicant""s later PCT Application No. PCT/US97/20874 (WO 9820939A2) further describes the manner in which xe2x80x9cxe2x80x98moldxe2x80x99 will refer to the portion or portions of an apparatus of the invention used to receive, constrain, shape and/or retain a flowable biomaterial in the course of delivering and curing the biomaterial in situ. A mold may include or rely upon natural tissues (such as the annular shell of an intervertebral disc) for at least a portion of its structure, conformation or function. The mold, in turn, is responsible, at least in part, for determining the position and final dimensions of the cured prosthetic implant. As such, its dimensions and other physical characteristics can be predetermined to provide an optimal combination of such properties as the ability to be delivered to a site using minimally invasive means, filled with biomaterial, and optionally, then remain in place as or at the interface between cured biomaterial and natural tissue. In a particularly preferred embodiment the mold material can itself become integral to the body of the cured biomaterial.xe2x80x9d
Applicant""s own use of such mold apparatuses to date has concentrated largely on the use of thin, extensible balloons adapted to be positioned and then filled in situ with curable biomaterial, with particular use as a replacement for the intervertebral disc following microdiscetomy. In turn, there has been considerably less focus, to date, on the use of any such molds in other joints, such as the knee. FIGS. 6 and 7 of Applicant""s PCT Publication No. WO 920939 A2, for instance, shows a balloon and corresponding drilling template for use in knee surgery, the balloon having foot portions protruding from a generally ovoid inflatable portion.
Finally, U.S. Pat. No. 6,206,927 describes a self-centering meniscal prosthesis device suitable for minimally invasive, surgical implantation into the cavity between a femoral condyle and the corresponding tibial plateau is composed of a hard, high modulus material shaped such that the contour of the device and the natural articulation of the knee exerts a restoring force on the free-floating device. In what appears to be a related manner, Sulzer has introduced a unicompartmental interpositional spacer to treat osteoarthritis in the knee. See xe2x80x9cLittle Device Could Pack a Big Punchxe2x80x9d, Sulzer Medica Journal Edition 2/2000 (www.sulzermedica.com/media/smj-full-tex/2000/0002-full-text-6.html). The device is described as a metallic kidney-shaped insert which fills in for the damaged cartilage between the femur and the tibia.
Such a metallic device, as described in either the Fell patent and/or Sulzer""s product literature, is described as appropriate for use in younger patients with moderate to severe chondromalacia, particularly since the product provides a hard, self-centering meniscal device that is xe2x80x9cdevoid of physical means that fix its locationxe2x80x9d. In so doing, the device of Fell et al. tends to require a significant amount of intact cartilage and meniscus. Applicant""s own products to date, including those improved embodiments described herein, have been largely geared toward more elderly patients, where such healthy cartilage is lacking. In turn, Applicant""s devices tend to provide angular correction and improved anchoring of the implant at the joint surface.
The recently issued Search Report in parent application PCT/US01/41908 includes two references, namely DE 19823325C1 and DE 4339895 C1 directed to multipart devices that include portions mechanically affixed to bone, and in turn, are unrelated to a polymeric interpositional device of the type presently claimed.
In spite of developments to date, there remains a need for a joint prosthesis system that provides an optimal combination of properties such as ease of preparation and use, and performance within the body.